Greenpois0n RC5 now allows you to jailbreak iOS 4.2.1 untethered on most devices including iPhone 4 and iPad. The best part? You won't need any SHSH blobs saved. redsn0w beta required you to have 4.2b3 blobs saved (and it was pretty unstable). Hopefully greenpois0n is going to be a much smoother experience for you guys. Hit the jump for a walkthrough on how to jailbreak iOS 4.2.1 with greenpois0n and for the answers to some commonly asked questions.

What devices will greenpois0n RC5 jailbreak?

iPhone 4/3GS

iPad

iPod Touch 2G/3G/4G

AppleTV second generation

You'll need to be running iOS 4.2.1 in order for this version of greenpois0n to work (4.1.1 for AppleTV second generation users).

Should I do a full stock restore first?

In short, most likely. If you're already stock and haven't been jailbroken, you're fine. Still back up your phone first in case anything goes wrong.

If you are currently jailbroken on 4.1, yes. Do a full stock restore to 4.2.1 and restore as a new iPhone. After jailbreaking, I still don't recommend restoring from a backup. Old jailbreak pieces can come with your backup and cause issues for you. Just my personal recommendation.

If you are currently tethered on 4.2.1 via redsn0w, you should be able to just run greepois0n right over your current jailbreak to untether. Some of the devs are saying if you have issues installing Cydia via greenpois0n after running it, simply run redsn0w again and let it re-install Cydia. Basically, as long as you aren't running a Monte version jailbreak on 4.2.1, you should be able to run greenpois0n to untether.

Will this jailbreak iOS 4.3 beta?

No. You'll have to wait a bit longer on a tested jailbreak for 4.3.

Jailbreaking iOS 4.2.1 via Greenpois0n

Download greenpois0n onto your Mac. (Some users have been reporting the servers being down. If you can't get it to download right away, just be patient. Their servers are probably just lagging from all the traffic. There are a few mirrors out there so be sure to check the comments for the latest updates on those.

Plug your iPhone, iPod Touch, iPad, or AppleTV in via USB (make sure the power is off) and follow the on-screen instructions to enter DFU mode.

Greenpois0n will recognize when your phone is properly in DFU mode and start to do its thing. After it's done, you'll see a Loader icon on your homescreen. Tap it and install Cydia. (Note: This only differs for AppleTV jailbreakers. You'll be done but need to continue accessing and installing apps via Terminal and SSH.)

You're done! Restore all your stuff (if you choose to or were stock before) and enjoy being jailbroken!

Note: Some users in the comments have been reporting sometimes the initializing error is a result of not holding the home button long enough when entering DFU mode. Even when the text is not greyed out anymore, continue holding the home button if you're getting the Initializing error even after trying Greenpois0n RC5 version 2.

There's some incomplete information here about how to do this.
Iphone/ipad needs to be plugged in first and then turned off before the greenpois0n app is run. Next, follow the directions on the greenpois0n screen when you hit JAILBREAK button.

I'm getting this messages on a black screen:
Unable to fing gBdevList
Unable to find fsmount
Unable to find fsunmount
Unable to find fsloadfile
And get stuck there.
I'm trying it on an already redwnow jailbroken phone.

Actually, yes you can. I said restore if you're on 4.1. If you were tethered on 4.2.1 already, you don't have to restore.
When you use redsn0w to tethered boot, you are essentially re-jailbreaking everytime.

Follow the on screen instructions should have covered that. Greenpois0n tells you what to do. If I have to read you the directions off the screen, that is probably a good indication you shouldn't be jailbreaking ;)

Allyson,
There are a lot of folks having issues with jailbreaking(modmyi.com forums or tipb forums). Mine worked because I plugged it in and then turned it off before I followed the onscreen instructions.
No need to be offensive in your tone.

This is listed all over as an "at your own risk" proposition.
If you can't read and comprehend, and act in accordance with instruction, you run the risk of borking your phone.
This has always been clear.
She's a blogger. It's not her job to coddle you.
This works, if done per instruction. The end.

Derek- If you write a GUIDE that says "How To" then I would expect the documentation to be complete. I was merely pointing out what else needs to be written in a GUIDE.
I am not expecting coddling. Mine jb worked the first time while I know other's didn't.
I guess you woke up on the wrong side of the bed. You seem to be looking for a fight.

Derek. Don't assume Derk, or myself, can't jailbreak. I've jailbroken every model up until iPhone 4 with no problems. Not the point at all.
The point is that this is an incomplete "how to" for those unfamiliar with the process. It's always vague, presumptuous instructions like this, from aloof techies, that lead to people (who are unfamiliar) having problems. And to suggest that anyone, who isn't a mind reader, shouldn't be jailbreaking in the first place, is simply as arrogant as one can get.
There is zero point in posting an "almost how to". Period. :roll:

Oh my goodness, I assumed that people could read some on screen instructions within greepois0n. i am such a terrible person.
To all of you saying I wasn’t specific enough, no, I did not feel the need to retype what greenpois0n already clearly TELLS you to do in the on-screen instructions. If you can not follow instructions, I still stand by the fact you should not jailbreak. (And no, I do not suggest people that know nothing about jailbreaking to do it. read up on it first, that’s why we have beginner’s guides. Read those and come back to this post). Greenpois0n is an extremely easy tool to use if you follow the instructions.
I answered the most common questions and concerns, told you where to download greenpois0n, how to run it, etc… if you can not follow the instructions on screen, again, don’t jailbreak.
(and yes monk, i deleted your comment. if you can't post like an adult, i'll delete your comments.)

@fastlane @derk and @monk
you 3 are out to pick a fight and nitpick. you win, I added "make sure the phone is powered off"
I also took a look around most other popular tutorials, they aren't much different than this one. the tool is easy to use. i'm not being arrogant in assuming all people are "techies". The tool really is that simple. Like I said, we have tons of beginners guides and tutorials for beginners (most of them written by me). If you didn't notice, those are also linked in the article, for that reason. Please don't assume anything. I help people consistently on twitter, in the forums, and via post ups. It's users like yourselves that make me NOT want to help people. Want to give me constructive criticism? That's perfectly fine. But if you can't act like an adult and choose your words appropriately, don't comment at all. Anything else rude or condescending will simply be deleted.

As far as I heard, the exploit used here was indeed patched in the 4.3 betas, so there was no reason to hold it back anymore since Apple found it by themselves. Therefore, the chronic-dev team released it now.
And if you save your 4.2.1 hashes now, there's a big chance you will be able to untether-jailbreak 4.3 once it is released through an updated redsn0w with the Monte technique included.

at this point im just waiting for 4.3 and dev teams work.
the only thing worth updating for in 4.2.1 is find my iphone , other than that kind of a waste of time going through the whole process to update.

SHSH blobs have nothing to do with unlocking. But if you want to keep your currently unlockable baseband, don't ever update/restore with an official IPSW simply through iTunes. iPhone 4 on official iOS 4.2.1 with the included baseband version is not unlockable at the moment, but MuscleNerd is working on it. Although you'll have to wait until iOS 4.3 is officially released.

I got this as well with my redsnow tethered iPad. Even after powering down and back up it just showed the recovery screen after a few seconds and itunes asked to restore. I used a program called RecBoot to force it out of recovery and then I just used redsnow to boot it. I think I will wait and see if they bring out an update for GreenPois0n before doing this again. I tried at least 5 times and it failed each time.

I think I am going to wait. The tethered Jail Break from redsn0w has no bugs and I havent had any problems. I reboot it once a week just to clear things out, but I have been pretty happy with it. From the comments etc, I can not tell if this JB is buggy or not. But I do think I will wait for Dev Team's JB. 4.3 is right around the corner also, so why go through all this set up if your going to be moving to 4.3.
thats my 2 cents.

That's nice of you, but the RC4 version is a few months old and doesn't jailbreak 4.2.1 ;)
The correct version is RC5 or RC5-2 respectively, and it has only been released for Mac at the moment, though a Windows version should come out soon.

Rinshu,
I'm getting the same thing. I've tried several times. The process seems to go well and I get the message that the jailbreak is complete and the ipad reboots. I'm not seeing the loader icon. I think also this is supposed to be installing a modded apple icon at start-up which I'm not seeing. My guess is the process is not working but I'm not seeing any kind of error. I follow the prompts and hold the buttons and release at the specified time. Screen goes dark, greenpoison seems to recognize that iPad is in DFU mode and does it's thing. Some have suggested holding tho home button for an extended period beyond the point when it says completed but when i do that eventually I just end up with the plug into itunes screen on the iPad which means, I think, that it has gone into recovery mode.
I've tried this, probably 8-10 times and something is obviously wrong.

Restored iPad, still found displays "Unable to fing gBdevList Unable to find fsmount Unable to find fsunmount Unable to find fsloadfile" then waited many many minutes ipad restarts with no loader. I assume ipad jailbreak fail. Any ideas?

Don't forget that if you do a stock restore and you're interested in reselling your phone at some point you have to preserve the baseband. Maintaining unlock-ability increases resale value quite a bit so keep that in mind.

modmyi.com <-- go here, read the responses under the greenposi0n topic. Grab the link to download the greenposi0nR5 from the responses. Install gpR5 reboot, then install cydia ONLY with the latest redsn0w. You now have a non-tethered jail broken phone with Cydia installed. The reason greenpois0n isn't working right now is because the app hits their website to run and the website is down. This is why we arent seeing the launcher install after it says complete. I followed the above steps and Im successfully jail-broken, running MiWi and have rebooted multiple times :)

I dont think so, the best answer I have seen for that is that you may not be holding the home button down long enough, hold it down long after the app says complete, I did it until the device rebooted.
I did it and had the Loader icon (on the last page) the first time, just nothing inside of it as of yet.

Ally,
Guide is perfectly fine. Jailbreaking, while not rocket science, isn't for everyone. Update link to new RC5, pat yourself on the back, and call it good. Following guide worked for me and my non-noob friends. Thanks for the post!

There are so many stinkin comments, that i stopped looking for what i'm about to suggest. So if it's already been said, please forgive me.
Allyson,
Would you mind providing an update that explains that some users may have to hold the home button the entire time that greenpois0n is jailbreaking? I was one of those users, but I did use what resources I already had at my fingertips to find the solution (hint/wink to all who are not using the CPU in front of you to HELP YOURSELF). I assumed (as I'm sure many others did) that when the text un-bolded, that that meant I could stop performing that action, seeing as that's how it performed whilst performing the entrance into DFU mode. I have seen a lot of comments/blogs/tweets/WHATEVER stating that they get the four lines and the "greenpois0n initialized" screen, as I experienced.
Just a thought...

I am not an expert in Jailbreaking by any stretch of the imagination. I am actually a novice. But I did "successfully" Jailbreak my phone with Green's newest release BUT the loader isn't working and I can't install cydia. It did work once and now the cydia app is just a blank icon that does nothing.
Why would this be released if everyone was going to have issues with it?
I do greatly appreciate the work they do. Has anyone found a way around this?

I get loading sources for a while then get this error message:
'Error
Please make sure that you're connected to the internet before launching loader'
I click on dismiss as its the only option here. Then only option available is to 'remove loader.app or cancel in options for open loader app.

greenpois0n doesn't work for me on windows or on Mac. (Ipad 4.2.1)
When i start greenpois0n and click to jailbreak it goes do DFU mode then the loader bar starts to work and after 5 of 10 seconds my Ipad restart and then i get the Connect to iTunes on my screen.
Can anyone Help??

I went from a tethered jailbreak done on redsnow to this one fairly smoothly. The first time I tried, I guess I let off the home button too soon. The second time, I just held it down longer. I've just rebooted it twice untethered to make sure.
The official site was offline so I just got it through a torrent site.

Before you tend to jailbreak your iphone, please right click on your device name(in iTunes) click on Transfer Purchases.
After you complete upgrade/jailbreak, Click on Sync App.
All Apps and Saved games will remains

You need to edit the line :
Will this jailbreak iOS 4.3 beta?
No. You’ll have to wait a bit longer on a tested jailbreak for 4.3.
It should read:
Will this jailbreak iOS 4.3 beta?
No. You’ll have to wait until just before the release of 4.4 on a tested jailbreak for 4.3.

hi everyone, i'm a newbie when it comes to Jailbreaking. I was finally able to download the app this morning. it's my first time and accidentaly deleted the Loader. Will I need the loader later? if so, how can get it again? do i need to run greenpois0n again? thanks

It works on my iphone4, yet needs to unlock, installed Cydia.
The most important part is timing. Make sure that the top right button is "sleep" and the round one on the face is "home", yes a bit confusing for a very old man like me.

Hi Everyone, I have previously jailbroken with limera1n on IOS 4.1. Is it possible for me to now jailbreak to 4.2.1 with Greenpoison and if I can are there any steps I need to take before doing so. Thanks!

under instruction number 4 in the article it says, "You’re done! Restore all your stuff (if you choose to or were stock before) and enjoy being jailbroken!"
Does that mean I should restore my phone from the backup I made right before I jailbroke? or should I just leave the phone the way it is after the jailbreak??

leave your phone the way it is. You made the restore for yourself in case you ever want to set it back to factory. Your phone jacks up and you need to go to AT&T or apple, simply restore and they cant tell it was ever jailbroke. (even though its legal)

Just installed greenpois0n over top of my tethered redsn0w jailbreak and it worked 1st try. I didn't backup/restore anything on my phone. Cydia works, all my settings stayed the same. Reboots just fine untethered.

umm sorry about that here is the continuation of the previous message. so i downloaded the greenpoison software. my itouch is off when i plug it onto my pc (laptop). i am able to put it successfully into dfu mode, but then it says failed, try again so do it again and same thing happens agains....so what do i do to fix this and also its a 2nd gen of ipod touch

Hi, i've been looking for an answer to this for some time now - please can someone give me some advice??
Ive recently purchased an iphone 4 16GB running on iOS 4.2.1 with baseband 03.10.01. The phone was purchased through vodafone whom have informed me that the iphone is factory unlocked or does not have a carrier/sim lock.
I am ONLY looking to jailbreak the device untethered so i can access 3rd party packages, obviously not unlock it. (On Mac OSX)
Several forums have suggested using redsnow 0.9.7b6, others have said this purely depends on an already tethered jailbroken iOS with the correct SHSH blobs to work.
Some recommend preserving baseband with tiny umbrella if you are going to jailbreak, others have recommended using greenpoisOn rc5, some say rc6…etc
All i want to know is what to use for Jailbreak only - untethered ofcourse.
Also
Will this affect my existing baseband at all?
Will there be any trace of it ever have been jailbroken if it is sent into Apple after a factory restore?
Many thanks to anyone who can answer all of these questions, or preferably has performed the same jailbreak as i am hoping to.

It's not working for me on iOS 4.2.1 modem firmware 03.10.01 . Greenpoison works and my iPhone starts scrolling through white-text-code like it is going to work, then it says "Error, no successful firmware download after 60000ms!! Giving up....."
Can anyone help me with this? plz and thx

woah..., i was so scared this wasn't going to work for my ipad, vie had people telling me, don't do it, it"ll mess ur ipad, but i did it, and the results.... me.... a happy man... well done, i've just got 1 more question, how do you get apps for free(the ones on sale)

Hi im trying to jailbreak my iphone 3gs with 4.2.1 and ive got the latest greenpois0n but it wont acknowledge that my phone has gone into DFU, anyone know why this is the case and how can i resolve this issue?

I just tried it. Everything went fine until Cydia kept on getting stuck. So I tried to reset my iTouch, then the screen went black. Then the greenpois0n logo was on. And also, when i tried the emergency shut down button, it kept on doing the same thing over and over again. So what do I do if it's turned off and stuck?

my ipad is jailbroken using redsnow and it is a tethered jailbreak, on 4.2, but when i just run greenpoison, and jailbreak it, nothing comes up, just an apple logo, and its stocks in there, ~.~ can some please help me?

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